The present invention relates to a headlamp for motor vehicles. More particularly, the invention relates to a vehicular headlamp of a type including a reflection-type lamp including a parabolic reflector and a light source, and two projection lamps, each having an elliptic reflector with a light source and a projection lens.
Headlamps may be broadly categorized into two types. In the first type of headlamp, as shown in FIGS. 6 and 7, a reflection lamp A including a parabolic reflector 4 with a light source 3 mounted in front of the reflector 4 is disposed within a lamp chamber defined by a lamp body 1 and a front cover 2. The light from the light source 3 when reflected by the parabolic reflector 4 is formed into a substantially parallel light beam. The parallel light beam is directed forwardly to a light distribution control step area S formed on a front cover 2. The light distribution control step area S distributes the light beam in given directions. In the second type of headlamp, as shown in those figures, a projection lamp B, which includes an elliptic reflector 5 with a light source 3 located near the first focal point of the reflector 5 and a projection lens 6 of which the focal point is coincident with the second focal point, is disposed within a lamp chamber. The projection lens 6 projects light beams in the form of a predetermined light distribution pattern.
The projection lamp B can use a reflector 5 which is smaller than that of the reflection lamp A. Accordingly, the lamp size can be reduced. The projection lamp is capable of projecting a large quantity of light. With these advantages, projection lamps have attracted a great of attention in recent years, and is frequently used for headlamps for motor vehicles.
It is not possible to significantly reduce the size of the reflection lamp A. However, the mirror surface color of the parabolic reflector 4 of such a lamp is splendid and brilliant when the lamp is not lit. Thus, the reflection lamp A has a good appearance. In this respect, the projection lamp A is superior to the projection lamp B.
Another type of headlamp has been proposed which obtains the advantages of both types of headlamps. In this headlamp, the reflection lamp A and the projection lamp B are arranged horizontally (side by side) within a single light chamber, as shown in FIGS. 6 and 7. In these figures, C indicates a clearance lamp of the reflection type including a parabolic reflector 7 and a light source 3a.
In the reflection lamp A, the parallel light beam, reflected by the reflector 4 and guided forwardly, must be transformed into a directive light distribution pattern. To this end, a diffusion step area S is formed in a portion of the front cover 2 corresponding to the parabolic reflector 4. In the projection lamp B, the forwardly directed light beam projected by the projection lens 6 is shaped into a distribution pattern by a light distribution control shade (shade for forming clear cut lines) provided therein. The thus-shaped light beam must pass directly through the front cover. To allow the beam to pass directly, no diffusion step area is formed in the portion of the front cover through which passes the light beam from the projection lamps. That is, this portion of the front cover is plain. As a result, the front cover of the conventional headlamp lacks uniformity in design, and its appearance is not particularly good since the diffusion step area S is locally formed on the front cover surface.